Electric clock



L. HAMMOND ELECTRIC CLOCK Filed Sept. l2, 1931 Sept. 3, 1935.

4 Sheets-Sheet 1v Y V aha/ M75)".- Zaa r6705 W-Z/ W fi 'fw.

Sept. 3, 1935. L. HAMMOND 2,013,208

' ELECTRIC CLO-CK I Fil' ed Sept. 12, 1951 4 Sheets-Sheet 2 W MJJM MM ,23 I

Sept. 3, 1935.

L. HAMMOND 2,013,208

' ELECTRIC CLOCK V Filed Sept. 12, 1931 4 Sheets-Sheet 3 152 g i I J00 5&5v 66 I laarew/Valwmmd 4414. dyk/i Sept. 3, 1935. I HAMMQND 2 ,013,208

ELECTRIC CLOCK Filed Sept. 12, 1931 4 Sheets-Sheet 4 24 46 Z 46 24 -Zaan9z&5 20 24 J4 Patented Sept. 3, 1935 1 UNITED. STATES PATENT OFFICE ELECTRIC CLOCK Application September 12, 1931, Serial No. 562,460

17 Claims.

My invention relates generally to clocks, and more particularly to the construction of electric clocks. Almost since the introduction of clocks of various types, they have been generally constructed by mounting the operating mechanism on a plurality (usually two) of metallic frame plates, the mechanism assembled on these plates inserted and secured in a case, and the opening in the back of the case closed by a back cover., It

is one of the primary objects of my invention greatly to improve the general construction of clocks, especially synchronous electric clocks, by utilizing a'single member which not only forms one of the two mechanism supporting frame plates, but also forms the back cover for the case.

A further object is to provide an improved electric clock in which one of the mechanism supporting frame plates serves also as an insulating terminal block for the electrical connections to the clock.

A further object is to provide an improved electric clock in which at least one of the mechanism supporting frame plates is molded of an insulating material.

A further object is to provide an electric clock having a unitary integral member serving as the back cover of the case, one of the frame plates, and as a connection plate.

A further object is to provide .an improved electric clock having a cover plate formed of non-magnetic material and serving as a frame plate and mounting plate for the coil and poles of an electric motor.

A further object is to provide an improved electric clock having a pair of frame plates molded of an insulating material and having in terengaging alining means in which one of said plates serves as the back cover and, by being 40 secured to the clock case, holds the complete mechanism in place within the case.

A further object is to provide an, electric clock having improved shaft bearings.

A further object is to provide an improved method of assembling electric clocks.

A further object is to provide an improved form of friction and inertia elements for synchronous clock motors.

Other objects will appear from the following description, reference being had to the accompanying drawings, in which I Figure l is a front elevation of the clock of m invention;

Figure 2 is a side elevation thereof;

Figure 3 is a rear elevation thereof;

Figure 4 is a side elevation of the frame plates, portions thereof being shown in fragmentary section;

Figure 5 is a rear elevation of the clock case, a part thereof being shown in fragmentary section;

Figure 6 is a front elevation of the front plate;

Figure 7 is a vertical sectional view taken on the line 'l-! of Fig. 3;

Figure 8 is a developed sectional view showing the gear train and the frame plate construction;

Figure 9 is an elevation of a sub-assembly, including the rear frame plate, motor, and some of the gear train;

Figure 10 is a fragmentary section taken on the line l0l0 of Fig. 3, and illustrating the method of mounting the field coil of the motor;

Figure 11 is a detail showing the field coil terminal connections;

Figure 12 is a fragmentary section taken on the line i2-I2 of Fig. 3, and illustrating the method of assembling the clock mechanism in the case;

Figure 13 shows the shape of the dial; and

Figures 14 and 15 are detail views illustrating the field pieces of the motor.

The clock comprises a case which is preferably molded of a phenol condensation product, as shown in Figs. 1, 2, 5 and 7, and has a circular face opening 22 formed in the front thereof. The case is in the form of a relatively thin shell which is illustrated as generally square in vertical section but may of course be made of any suitable design or shape. The case has molded integrally therewith a plurality of bosses 24, which are provided with tapped holes 26, located in the corners of the case, and has one or more substantially semi-circular recesses 28 molded in the rear face of the front wall Ill-of the case. The case is preferably supported upon a plurality of soft rubber feet 32 which are pressed into suitable sockets 34 formed in the bottom of the case 20.

The clock mechanism is supported by a pair" ofrmolded frame plates 36 and 38. These plates are preferably made of a phenol condensation product or any similar substance which may be molded, and which is strong, is a good electrical insulator, or at least is non-magnetic, which forms a suitable bearing surface, and which may be obtained at a reasonably low cost; The front the peripheral rim 42 of the front frame plate 36 and are adapted to seat within the recesses 28 formed in the front wall 30 of the case 20, thereby determining the correct position of the frame plate 36 with respect to the case 20. The front frame plate has a plurality of forwardly and rearwardly extending bosses surrounding bearing openings which will hereinafter be described in detail.

The rear frame plate 38 is substantially square in shape so as to fit snugly within the case 20, and is provided with forward extending bosses 50 which at their ends have dowel recesses 52 to receive the dowel projections 48. The rear frame plate 38 is adapted to be secured to the case 20 by a plurality of cap screws 54 which pass freely through cored openings 56 formed in the rear frame plate 38, and are threaded in the tapped holes 26.

It will be noted that the principal means for holding the front plate 36 in alinement with the rear plate 38 is the set of lugs 46 and 50 which, through their interengaging dowels. and sockets respectively, maintain the plates in proper spaced relation and in proper alinement. The dowel and socket connection does not, however, hold the plates together. The plates are held together by means of .the clamping pressure exerted by the cap screws 54 which, through the lugs or posts 46, 50, press the front plate against a dial 58, the latter in turn pressing the crystal 60 against an inwardly extending bezel flange 62 formed about the opening 22 in the front wall of the case 20. The front plate and dial are held in properly oriented position by the engagement of the lugs 46 of the front plate and tabs 58 of the dial 58 in recesses 28. Thus, by the use of a few cap screws the crystal, dial, frame plates and entire mechanism' are secured together and firmly mounted within the case.

The rear frame plate 38, as previously stated, is preferably molded of a phenol condensation product and has an inwardly or forwardly extending flange 64 which reinforces the edge of the plate. The lower portion of the plate has an outwardly extending hood 66 to form a space to receive a coil 68 of a motor. The rear of the hood also serves as a convenient surface for the location of operating instructions, manufacturers name, etc., which are preferably formed in relief by the molding die.

The motor comprises field pieces 'I0,"I2 of suitable magnetic material (Figs. 14 and 15). These field pieces have pole teeth I4 formed thereon for cooperation with the teeth I6 of a magnetic rotor I8. The field pieces I0 and I2 have portions 80, 82 respectively, which project through the central opening in the coil 68 and, together with a plurality of rectangular shaped lamina 84, are secured to the rear plate 38 by means of bolts 86. The heads of the bolts 86 rest in complementary recesses 88 formed in the plate 38 so as to facilitate threading the nuts on the bolts. The portion 82 of the field piece I2 is offset so as to lie adjacent the portion of the field piece I0. The field piece I2 has a bolt hole formed therein to receive a bolt 92 (Fig. 9), the head of which is held in a complementary recess 84 in the frame plate, and has other suitably located holes to permit free passage of various shafts of the gear train. i

The ends of the wire forming the" coil 68 are secured to the ends of the conductors of an extension cord 96 in conducting relationship therewith by means of screws 98 (Fig. 11) threaded in suitable bosses I00 formed on the inside of the frame plate 38. The extension cord 96 is threaded through an opening I02 formed adjacent the bottom of the hood 66, the two conductors thereof being knotted together so as to prevent the ends of the conductors from being pulled loose from the screws 98.

The rotor I8 (Fig. 8) is secured to a non-magnetic metallic hub I04 which in turn is rigidly secured to a shaft I06. An inertia and friction element I08, preferably made of a phenol con- I densation product, is rotatably mounted upon the hub I04, being held thereon by a flange IIO formed at the end of the hub. The friction and inertia element I08 has the enlarged bore II2 which is provided with a counterbore I I4 at each end thereof. made 01' a linen impregnated with a phenol condensation product, are pressed into said counterbores H4 and fit relatively loosely around the hub I04. Thespace within the bore II2 between the washers H6 is filled with a lubricant, preferably wicking II8 soaked in oil. The rearward end of the rotor shaft I06 projects into a socket I20 formed in the rear frame and cover plate 38, the socket being counterbored to receive a bearing washer I22 which is preferably the same material as the washers H6. The space within the socket I20 around the shaft I06 is filled with oil-soaked wicking I24 or other suitable lubricating means. The bearing for the other end of the rotor shaft I06 is similarly formed by a socket I26 in the front plate 36, and a washer I28 pressed into a counterbore I30 of the socket. The Washers II6, I 22 and I28 expand slightly upon being moistened with oil so that they will, after being pressed into place, be tightly retained in position. The washers of linen impregnated with Bearing washers H6, preferablyphenol condensation product form excellent.

. bearings even when dry, and when kept slightly lubricated will not show appreciable wear during years of use.

.A drive pinion I32 is non-rotatably secured to the shaft I06 and meshes with a gear I34 which is rigidly secured to a pinion I36 fixed to a shaft I38. The forward end of the shaft I38 projects through a bearing hole I40 formed in the front plate 36 and at its forward extremity carries a disc I42 of fiber or other suitable material which is positioned within a recess I44 formed in the front plate. The face of the flasher disc I42 is painted or printed with sectors of different colors, or is otherwise suitably marked so that the portion thereof which is visible through an aperture I46 formed in the dial 58 will a1ternately change color and thus form a flashing in,- dlcation that the clock is in operation. The pinion I36 drives a gear I48 which is secured to a pinion I50 fixed to a shaft I52. The ends of the shaft I 52 project into suitable bearing sockets E54 and I56 formed in the frame plates 36 and 38 respectively. The pinion I50 drives a gear I58 (shown in two places'in Fig. 8) which is secured to a pinion I60 fixed to a shaft I62, the latter having its ends bearing in sockets I64, I66 formed in the frame plates 36 and respectively. The pinion I60 drives a gear I68 (as shown in two places in Fig. 8.), which is secured to a pinion M0 rotatable upon shaft I52. The pinion I70 meshes with a gear I12 which is rotatably mountgear I 82 secured to a pinion I84 which is rotatable 1 upon the shaft I 82. The pinion I 8 drives a gear I86 secured to an hour hand sleeve I88 rotatable upon the shaft I18, the sleeve I88 having a suitable bearing in an opening I98, formed in the front frame plate 38. The shaft I18 projects beyond the end of the sleeve I88 and has a minute hand I82 secured thereto, the hour hand I94 being secured to the sleeve I88. The minute hand shaft I16 has a collar I98 secured thereto to hold the shaft against longitudinal movement relative to, the rear frame plate 88 and at its rearward extremity carries a setting thumb piece I98. The shaft I36 is likewise held against longitudinal movement in the frame plate 88 by a collar 288 pressed over the shaft, and at its rear extremity has a knurled finger piece 282 tightly secured thereto so that the shaft I38 may readily be manually twirled to start the electric motor.

The clock above described can be very quickly and easily assembled. The rotor assembly and the various elements of the gear train are assembled upon the rear frame and cover plate 38.

A suitable jig or fixture may be provided to hold the shafts in proper position and the front plate 36 may then be slipped over the front 'ends of the shafts, bringing the dowels and recesses of the lugs 46 and 58 respectively into registry. Thereafter, the flasher disc I82 is pressed upon its shaft I38, the dial 58 placed upon the front plate 38, the hands pressed over their respective shafts, the crystal placed over the dial, and the whole assembly then inserted in the case and secured therein by means of the cap screws 58. In assembling in this manner, the only operations requiring any appreciable time are the securing of the field pieces I8, I2 to the back cover plate by means of the bolts 92 and 86, and the fastening of the whole assembly in the case by turning in the cap screws 58. The parts are so formed that the complete assembly operation requires but a few minutes.

The above described construction has innumerable advantages over clock constructions at present employed. The front frame plate and the combined rear frame plate and cover plate being made of a phenol condensation product or other suitable moldable material, may be non-magnetic, non-conducting, non-inflammable, not affected by oil, and tend to reduce vibration and noise. It will be noted that most of the bearings are in the form of sockets and that the back of the clock is therefore substantially closed to the entrance of dust and dirt around the bearings. The front plate is held accurately spaced from the rear cover plate by the lugs on the plates with their interengaging dowels and sockets. The bezel, spacing ring, back cover plate and a large number of other parts usually used are entirely elim inated. I

Since the back cover of the clock is molded, themakers name and similar identifying markings customarily used in clocks may be molded originally as an integral part of the cover, thus elimmating the necessity of a name plate and its attaching means.

The fact that the rear cover plate is of insulatingmaterial makes it possible easily to connect the field winding of the motor to the ends of the extension cord without making it necessary to use solderedconnections.

Since the rear cover plate is molded, suitable depressions may be formed therein for receiving the heads of the bolts used to attach the field pieces of the motor and hold the bolt heads against rotation during the assembly operation,

The field pieces are shaped so that substantial portions thereof lie adjacent each other throughout the length of the coil, and the magnetic'fiux generated by the coil is thus efficiently conducted to the field poles. Only three bolts are utilized in attaching the field pieces and coil to the back cover and the construction is such that the field pieces and coils may easily be set in proper position (with the aid of a suitable assembly fixture) and readily tightened in place.

The gear train is extremely simple. The dial and the rotor shaft bearings, as well as the bearings for the other shafts, may easily be made of any desired length efiiciently to bear the load imposed for an extended period of time without appreciable wear. Since the back cover plate is molded, it may readily be made to conform to the requirements of the spacing of the operating mechanism of any desired design, as, for example, by the provision of the hood 86 to allow proper positioning of the coil 68. The dial 58 being made of a heavy paper or thin cardboard may be economically printed with suitable dial indicia, the dial at the same time serving as a pressure distributing gasket for the crystal.

In operation, the extension cord 96 is connected to a suitable source of alternating current of regulated frequency, and the finger piece 282 manually twirled to start the motor. The motor is of the non-self-starting type, as generally disclosed in my Patents No. 1,719,805, granted July 2, 1929, and No. 1,797,912, granted March 24, 1931. The friction and inertia element I88 will cause the rotor of the motor to fall into step as it decelerates from the super-synchronous speed at which it was launched by twirling the finger piece 282, and after having fallen in step the said friction and inertia element will act as an anti-hunting device to prevent the motor from stopping. The clock is set to the correct time in the usual manner by rotating the thumb piece I98, the frictional connection formed by the spring I18 permitting setting of the hands of the clock without rotation of the entire gear train.

While I have shown and described a specific embodiment of my invention, it will be apparent to those skilled in the art that various changes and modifications may be made, all of which come within the scope of the claims which follow.

I claim:

1. In an electric clock, the combination of a case having an aperture therein, a frame element molded of a non-magnetic material, an electric motor and gear train driven thereby supported by said frame element, and means for securing said element to said case thereby holding said motor and gear train within the case, said element forming a cover for the aperture at the back 'of the case.

. of frame plates, one of said plates being molded of a phenol condensation product and forming a cover for the opening in said case, an electric motor mounted upon said molded plate, a gear train supported by said plates and driven by said motor, and means for holding said plates in spaced relation within the opening in said case.

4. In. an electric clock, the combination of a case having an opening formed therein, a pair of frame plates, one of said plates forming a closure for the opening in said case, said plate being molded of non-magnetic material and having bearing sockets formed therein, a gear train operatively mounted upon said plates, some of the shafts of said train being rotatably carried in I said sockets, and an electric motor having field pieces and a field coil, said field pieces and coil being secured to said molded plate.

5. In an electric clock, the combination of a case having an opening therein, an electric motor-driven clock mechanism, a pair of mechanism supporting frame plates within said opening, one of said plates being molded of nonmagnetic material and forming the back cover for said opening, and means to secure said molded plate to said case.

6. In an electric clock, the combination of a case, an electric motor and gear train driven by said motor, a front plate partially supporting said 7 netic material forming a combined rear frame" plate for said gear train and back cover for said case.

8. In an electric clock, the combination of a case, an electric motor having electrical connections for supplying current thereto, a gear train.

driven by said motor, a front plate for supporting said gear train, and a member molded of insulating material serving as a support for said motor and said gear train, as a closure wall for said case and as an insulating panel for supporting the electrical connections for said motor.

9. In an electric clock, the combination of a case, an electric motor, a speed reducing gear train comprising a plurality of gears and shafts, a front plate having bearings formed therein for supporting one end of each of a plurality of said shafts, and a member of non-magnetic material having sockets molded therein to form bearings for the other ends of each of said plurality of shafts, said member forming a support for the field coil of said motor and constituting the back cover of said case.

10. In an electric clock, the combination of a case, an electric motor, a clock mechanism driven thereby, and a combined frame plate for said v motor and mechanism and back cover for said case, said plate and cover being integrally molded of an insulating material and having a hood portion projecting rearwardly from the general plane thereof to form an internal recess for the field coil of said electric motor.

11. In an electric clock, the combination of a case, a front frame plate, a combined rear frame plate and back cover for said case, said plates being molded of non-magnetic material and having opposed projecting lugs with interengaging alining and spacing means at their extremities, an electric motor and clock mechanism mounted upon said plates, interengaging means on saidfront frame plate and case to hold said parts in a predetermined position to preclude rotation thereof relative to one another, and means for securing said combined rear frame plate and back cover to said case, said means being operative to force said detachable interengaging means into tight engagement and said front frame plate tightly into its predetermined position in said case.

12. 'In an electric clock, the combination of an electric motor and gear train driven thereby, a pair of frame plates molded of a non-magnetic material for supporting said motor and gear train, one of said plates having posts formed integrally therewith and the other of said plates having, means molded integrally therewith for cooperative engagement with said posts thereby to space said frame plates, and means for forcing said'frame plates together.

13. In an electric clock, the combination of a hollow case having a face aperture in the front wall thereof and a bezel flange surrounding said aperture, a crystal of larger dimensions than said opening and adapted to be held in place by said flange, a clock mechanism having a front plate, interengaging means on said front plate and case to prevent relative rotation between said parts, a dial of compressible material, interengaging means on said dial and said case for holding the former against rotary movement relative to the latter, and means to force said front plate against said dial and said dial against said crystal thereby to hold said crystal against said bezel flange.

14. In an electric clock, the combination of a case having an opening formed therein, a pair of frame plates, one of said plates being molded of a non-magnetic material, an electric motor mounted upon said molded plate, a gear train supported by said plates and driven by said motor, and means molded integrally with said molded plate for holding the latter spaced from the other plate.

15. In an electric clock, the combination of a case having an opening therein, an electric motor-driven clock mechanism, a pair of frame plates for supporting said mechanism within said opening, one of said plates being molded of an insulating material and forming the back cover for said opening, and means associated with said last named plate to secure said plates and mechanism within said case,

16. In an electric clock, the combination of an 

